1. Field of the Invention
The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus suitable for use as a compound eye image pickup apparatus.
2. Related Background Art
A compound eye image pickup apparatus has been proposed in order to form a wide panoramic image or high precision image, as disclosed, for example, in Japanese Patent Application Laid-open No. 7-67020. This compound eye image pickup apparatus has a plurality of image pickup systems each having an optical focussing system and an image pickup element, and forms a single synthesized image from image signals obtained by these image pickup devices.
Such a compound eye image pickup apparatus is, however, associated with a problem that an area of an image of a back object not picked up because of the presence of a front object differs at each image pickup element. FIGS. 14, 15A and 15B illustrate how this problem occurs. In FIG. 14, reference numerals 131 to 133 represent a spherical object, and reference numerals 134 and 135 represent an eye position from which each object is observed. FIGS. 15A and 15B show the objects 131 to 133 as viewed from the eye positions 134 and 135. As the objects 131 to 133 are viewed from the eye position 134, the object 132 is partially shaded by the object 131 as shown in FIG. 15A. In contrast, as the objects are viewed from the eye position 135, although the object 132 is not shaded by the object 132, the object 133 is completely shaded by the object 131 as shown in FIG. 15B. Therefore, even if two images with a partially overlapped area taken from different eye positions are synthesized to form a panoramic image, since the overlapped areas of the two images are not identical to each other, it is difficult to synthesize the two images such that the joint area between two overlapped areas does not become conspicuous.
There is another problem that the shape of a cubic object changes with an eye position. FIGS. 16, 17A and 17B illustrate how this problem occurs. In FIG. 16, reference numeral 156 represents an object having a cubic form, and reference numerals 157 and 158 represent an eye position. FIGS. 17A and 17B show the image of the object 156 as viewed from the different eye positions 157 and 158. As the object 156 is viewed from the eye position 157, the object has an image of generally a square as shown in FIG. 17A, whereas as the object 156 is viewed from the eye position 158, it has an image of two trapezoids having one common side as shown in FIG. 17B. Therefore, even if two images with a partially overlapped area taken from different eye positions are synthesized to form a panoramic image, since the overlapped areas of the two images have different shapes, it is impossible to synthesize the two images.
As above, a panoramic image taken with a conventional compound eye image pickup apparatus is often synthesized into an unsatisfactory image, because of the above problems caused by different image pickup positions of right and left image pickup systems. Such a difference between image pickup positions of right and left image pickup systems is hereinafter called a parallax.